On Saturday 06 March 2010 17:26:32 Mile Davidovic wrote:
> Hello
> I am wondering if someone has managed to create small Qt based app
> which can deal with video (I want to have OSD and video in same time).
>
> What can be best starting point for this?
>
Hi,
I'm integrating GStreamer with Qt. Since GStreamer-ti plugins provide
acceleration for GStreamer, this combination has everything I need.
Following can be a starting point:
1) Create a filesystem image from Narcissus[1]. Most of the DaVinci processors
are present. My suggestion is to use unstable branch. Either select
gstreamer-ti plugins while creating the image or install those while
running on your device. Package list can be found at [2].
2) Try gstreamer plugins using the command line, i.e. gst-launch. Many example
pipelines can be found at [3]. Some examples present at the filesystem as
well.
3) After deciding which pipelines are suitable for your case, set-up an
OpenEmbedded environment. This will permit you compile your own
applications with Qt.
4) Write your Qt application and integrate your pipelines you decided in step
2 using 'gst_parse_launch' command from GStreamer library. More
information and examples about using GStreamer can be found at [4].
5) Use attribute window for controlling video and osd layers in your
application. An example code is attached at the end of this mail.
Best regards,
Caglar
[1] http://www.angstrom-distribution.org/narcissus
[2] http://www.angstrom-distribution.org/repo/
[3] http://wiki.davincidsp.com/index.php/Example_GStreamer_Pipelines
[4]
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/index.html
___________________________________________________________________________
/**
* DM6446 has separate framebuffers(windows) for OSD and Video layers.
* This function controls attribute window for transparency adjustment.
*
* trans: A value between 0-127. 0 means Video visible, and 127 means OSD.
* x: Start horizontal offset, must be multiple of 32.
* y: Start vertical offset
* width: Horizontal length, must be multiple of 32.
* height: vertical length
*/
bool MainWindow::SetOsdTransparency(unsigned char trans, unsigned int x,
unsigned int y, unsigned int width, unsigned int height)
{
struct fb_var_screeninfo vScreenInfo;
struct fb_fix_screeninfo fScreenInfo;
unsigned short *attrDisplay;
int attrSize;
/*
* Check parameters
*/
if(((x & 31) != 0) || ((width & 31) != 0)) {
qDebug() << "Wrong tranparency width/x values";
return false;
}
int fd = open("/dev/fb2", O_RDWR);
if(fd < 0) {
qDebug() << "Error opening attribute window";
return false;// err;
}
if (ioctl(fd, FBIOGET_FSCREENINFO, &fScreenInfo) == -1) {
::close(fd);
qDebug() << "Unable to get screen info";
return false;
}
if (ioctl(fd, FBIOGET_VSCREENINFO, &vScreenInfo) == -1) {
qDebug() << "Unable to get screen info";
::close(fd);
return false;
}
attrSize = fScreenInfo.line_length * vScreenInfo.yres;
/* Map the attribute window to this user space process */
attrDisplay = (unsigned short *) mmap(NULL, attrSize,
PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if (attrDisplay == MAP_FAILED) {
qDebug() << "Unable to map attribute window";
::close(fd);
return false;
}
/* Fill the window with the new attribute value */
if(height < vScreenInfo.yres) {
for(unsigned int i = y; i < y + height; i++) {
int start = fScreenInfo.line_length * i + x / 2;
int size = (width + x) / 2 < fScreenInfo.line_length ?
width / 2 : fScreenInfo.line_length - x
/ 2;
memset(attrDisplay + start / 2, trans, size);
}
} else
memset(attrDisplay, trans, attrSize);
munmap(attrDisplay, attrSize);
::close(fd);
return true;
}
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